High power dual-comb spectrometer system

Abstract

The present invention relates to a high-power dual-comb spectroscopy system, and also to a seed source system for a high-power dual-comb spectrometer, which is used to realize the dual-comb system of the present invention. The dual-comb spectroscopy system of the present invention includes a dual-wavelength mode-locked pulse seed source 1, a signal light wavelength division multiplexer 2, a first optical fiber amplifier 3, a second optical fiber amplifier 4, a first compressor 5, and a second compressor 6. Among them, the dual-wavelength mode-locked pulse seed source, the wavelength division multiplexer, the first amplifier 3, and the second amplifier 4 are constructed with a full polarization-maintaining optical fiber link to ensure system stability and reliability and immunity to external environmental disturbances. The first compressor 5 and the second compressor 6 are typical pulse compression devices constructed using spatial grating pairs, prism pairs, or prism pairs. The present invention realizes a femtosecond optical fiber dual-comb spectrometer system with high average power and high peak power, as well as a dual-comb seed source with a simple structure, long-term stability and reliability, immunity to environmental interference, and reproducibility; the present invention can realize a full polarization-maintaining all-fiber structure with good environmental stability, which can meet the requirements of operating in an environment outside the laboratory.

Description

Technical Field

[0001] The present invention belongs to the field of laser and laser detection, and in particular relates to an all-fiber high-power dual-comb spectrometer system which has a simple structure, is stable and reliable, and is easy to operate. Background Art

[0002] Dual-comb spectroscopy is a spectral resolution technology that enables fast, real-time, and high-precision detection. It utilizes two optical frequency combs with a slight frequency difference. During detection, one of the signal combs passes through the sample cell, preserving information about the sample's absorption and phase effects. The other comb's signal acts as interference light. The interference of the two combs' output lasers can be used to recover relevant information about the sample. Dual-comb spectroscopy has been applied in fields such as aircraft engine combustion field monitoring (201910988351.0), underwater interferometric ranging (201810601290.3), three-dimensional topography measurement (201810726961.9), and non-destructive monitoring of pathological sections (201710772396.5).

[0003] However, traditional dual-comb systems rely on two independent optical frequency combs, whose frequency and phase jitter are independent, significantly reducing their coherence. To improve the stability and accuracy of dual-comb systems, the two combs must be precisely locked to a certain frequency difference, requiring complex signal processing and circuit servo systems for each comb. As a result, dual-comb systems are confined to laboratories and can only be operated by professionals, greatly limiting their widespread application.

[0004] In recent years, the emergence of dual-wavelength mode-locked pulse lasers has attracted significant attention from researchers. Dual-wavelength mode-locked lasers can simultaneously generate mode-locked pulses of different wavelengths. Because the two wavelengths of mode-locked pulses originate from the same resonant cavity, they exhibit inherent coherence. Furthermore, due to the difference in refractive index when the different wavelength pulses propagate within the cavity, their repetition frequencies also differ slightly. Using them as the seed source for a dual-comb system can greatly simplify the system. However, related research reports have primarily focused on the operating band (1550 nm) of erbium-doped fiber lasers and non-polarization-maintaining devices based on single-mode fiber. The high-power scalability, long-term stability, and reliability of these lasers need to be further improved. Summary of the Invention

[0005] To address these issues, the present invention provides a dual-comb spectrometer system capable of high-power output. One objective is to develop a femtosecond fiber dual-comb spectrometer capable of high average and peak power output. Another objective is to provide a fully polarization-maintaining, all-fiber structure with a dual-wavelength mode-locked laser that produces dissipative soliton output. One of its primary applications is as a seed source for dual-comb spectrometers.

[0006] In order to achieve the above object, the technical solution adopted by the present invention is

[0007] A high-power dual-comb spectrometer system, the system comprising a dual-wavelength mode-locked pulse seed source (1), a signal output end of the dual-wavelength mode-locked pulse seed source (1) being connected to an input end of a signal light wavelength division multiplexer (2), an output end of the signal light wavelength division multiplexer (2) being connected to an input end of a first optical fiber amplifier (3) and an input end of a second optical fiber amplifier (4), respectively, and an output end of the first optical fiber amplifier (3) and the second optical fiber amplifier (4) being connected to a first compressor (5) and a second compressor (6), respectively, wherein the dual-wavelength mode-locked pulse seed source (1), the wavelength division multiplexer (2), the first optical fiber amplifier (3) and the second optical fiber amplifier (4) are constructed by a full polarization-maintaining optical fiber link, and the first compressor (5) and the second compressor (6) are typical pulse compression devices constructed by using a spatial grating pair, a prism pair or a prism pair;

[0008] The signal light wavelength division multiplexer (2) is a polarization-maintaining fiber beam splitter, which is used to split the dual-wavelength mode-locked pulse output by the seed source according to the central wavelength, so that the two wavelength mode-locked pulses are spatially split and used as signal light and interference light of the dual-comb system respectively.

[0009] The dual-wavelength mode-locked pulse seed source 1 includes a semiconductor pump diode LD, a pump wavelength division multiplexer, a gain fiber, a phase shifter, an output coupler, a central beam splitter, an angled splice, and a fiber reflector with a pigtail. Each fiber component is sequentially fused end-to-end to form a resonant cavity link.

[0010] The fiber amplifier includes an optical isolator, a wavelength division multiplexer, and a gain fiber. The fiber amplifier is a single-stage or multi-stage cascade amplifier structure, depending on the target output power. The gain fiber is a waveguide medium with a core doped with rare earth ions, which can be but is not limited to rare earth ions such as ytterbium, erbium, thulium, and neodymium.

[0011] First, the implementation principle of the high-power dual-comb spectrometer seed source in the present invention, the dual-wavelength fiber mode-locked pulse oscillator, is explained in detail:

[0012] In dual-wavelength mode-locked lasers, the multi-channel filtering effect within the resonant cavity is a key element in achieving this. The birefringence effect in single-mode fibers provides an easily achievable multi-channel filtering effect. Combined with a passive mode-locking mechanism, fiber-based dual-wavelength mode-locked lasers are relatively common. However, for stability and reliability reasons, dual-wavelength mode-locked lasers using fully polarization-maintaining fiber structures are more popular. This invention combines polarization-maintaining fiber with a Lyot filter to achieve multi-channel filtering in dual-wavelength mode-locked lasers, thereby realizing a fully polarization-maintaining fiber-based dual-wavelength mode-locked laser. The multi-channel filtering effect is demonstrated (using ytterbium-doped fiber operating in the 1030 nm band as an example): the spontaneous emission (ASE) within the laser resonator exhibits a distinct periodic multi-peak structure, forming a typical multi-channel filtering effect. With sufficiently strong pump power, spectral peaks at different locations within the resonant cavity are simultaneously excited. By balancing gain and competition, dual-wavelength mode-locked pulses can be output.

[0013] The beneficial effects of the present invention are:

[0014] A femtosecond fiber dual-comb spectrometer system with high average power and high peak power was realized;

[0015] A dual-wavelength mode-locked pulse oscillator, a dual-comb seed source with a simple structure, long-term stability and reliability, immunity to environmental interference, and reproducibility, has been realized.

[0016] The system can realize a fully polarization-maintaining, all-fiber structure with good environmental stability, which can meet the needs of operating in an outdoor environment. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 This is a high-power dual-comb spectrometer system in the 1030 nm band of the present invention

[0018] Figure 2 This is an embodiment diagram of the dual-wavelength mode-locked pulse oscillator of the present invention

[0019] Figure 3 Multi-channel filtering effect diagram in the present invention

[0020] Figure 4 Output spectrum of dual-wavelength mode-locked pulse seed source DETAILED DESCRIPTION

[0021] The present invention will be further described below with reference to specific embodiments and accompanying drawings.

[0022] Example 1: A high-power dual-comb spectrometer system in the 1030 nm band

[0023] like Figure 1As shown, a high-power dual-comb spectrometer system in the 1030 nm band is characterized by comprising a dual-wavelength mode-locked pulse seed source 1, a signal light wavelength division multiplexer 2, a first amplifier 3, a second amplifier 4, a first compressor 5 and a second compressor 6.

[0024] The dual-wavelength mode-locked pulse seed source 1, such as Figure 2 As shown, it includes a semiconductor diode (LD) 11, a pump wavelength division multiplexer 12, a gain fiber 13, a phase shifter 14, an output coupler 15, a fiber beam splitter 16, an angle fusion point 17 and a fiber reflector 18 with a pigtail.

[0025] Preferably, the semiconductor diode (LD) 11 is a semiconductor laser diode with a central wavelength of 976 nm, an output mode of single-mode optical fiber output, and a maximum output power of 600 mW, serving as the pump source of the seed source in the present invention.

[0026] The pump wavelength division multiplexer 12 is a three-port fiber optic device that can couple pump light (976 nm) and signal light (1030 nm) into a common port. The pump port is connected to the output port of the LD, and the common port is connected to the gain fiber.

[0027] The gain fiber 13 is an optical fiber with a core doped with ytterbium ions. As the gain medium in the laser of the present invention, the optical fiber can radiate spontaneous emission laser with a wavelength covering 1010-1100 nm after being excited by pump light.

[0028] The phase shifter 14 is a non-reciprocal phase shift element that provides different phase shifts for light transmitted in opposite directions, forming a fixed phase difference, and helping to establish the nonlinear amplifying loop mirror mode-locked pulse.

[0029] The output coupler 15 is a three-port fiber coupler with a beam splitting ratio of 10:90 in the embodiment. Port 10 is used to output mode-locked pulses.

[0030] The central beam splitter 16 is a four-port fiber coupler. It has a 50:50 splitting ratio and operates at a wavelength of 1030 nm, operating in the slow axis with isolation in the fast axis. The coupler's three fiber ports are connected to the phase shifter output, the wavelength division multiplexer signal port, and the laser's stretch amplifier. The other port can also serve as a pulse signal output.

[0031] The angle welding point 17 adopts the axis angle welding, that is, during the welding process, the fast axis (slow axis) of the two optical fibers are ensured to form an angle of 45°.

[0032] The fiber optic reflector 18 with a pigtail is preferably a fiber optic reflector in the 1030 wavelength band. The pigtail is a coupling fiber, preferably a PM980 fiber.

[0033] The wavelength division multiplexer 2 has an operating wavelength band of 1039 / 1042 nm and can spatially split the dual-wavelength pulses output by the dual-wavelength mode-locked pulse seed source.

[0034] The fiber amplifier includes an optical isolator, a wavelength division multiplexer, and a gain fiber. The fiber amplifier can be a single-stage amplifier or a multi-stage cascade amplifier structure, depending on the target output power. This is a typical structure and will not be described in detail in this invention.

[0035] The pulse compressor is a typical pulse compression device constructed using a spatial grating pair, a prism pair, or a grism pair. This is a typical structure and will not be described in detail in the present invention.

[0036] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, without departing from the technical principles of the present invention, several improvements and modifications can be made. For example, the passive mode-locking mechanism in the oscillator can be changed to other types, such as semiconductor saturable absorption mirror mode-locking or nonlinear polarization rotation mode-locking. These improvements and modifications should also be considered as the scope of protection of the present invention.

Claims

1. A high-power dual-comb spectrometer system, characterized by: The system comprises a dual-wavelength mode-locked pulse seed source (1), a signal output end of the dual-wavelength mode-locked pulse seed source (1) is connected to an input end of a signal light wavelength division multiplexer (2), an output end of the signal light wavelength division multiplexer (2) is respectively connected to the input ends of a first optical fiber amplifier (3) and a second optical fiber amplifier (4), and an output end of the first optical fiber amplifier (3) and the second optical fiber amplifier (4) is respectively connected to a first compressor (5) and a second compressor (6), wherein the dual-wavelength mode-locked pulse seed source (1), the wavelength division multiplexer (2), the first optical fiber amplifier (3), and the second optical fiber amplifier (4) are constructed by a full polarization-maintaining optical fiber link, and the first compressor (5) and the second compressor (6) are typical pulse compression devices constructed by using a spatial grating pair, a prism pair, or a prism pair; The signal light wavelength division multiplexer (2) is a polarization-maintaining fiber beam splitter, which is used to split the dual-wavelength mode-locked pulse output by the seed source according to the central wavelength, so that the two wavelength mode-locked pulses are spatially split and used as signal light and interference light of the dual-comb system respectively.

2. The high-power dual-comb spectrometer system according to claim 1, wherein: The dual-wavelength mode-locked pulse seed source (1) comprises a semiconductor pump diode LD, a pump wavelength division multiplexer, a gain fiber, a phase shifter, an output coupler, a central beam splitter, an angle fusion point, and a fiber reflector with a pigtail, and each fiber device is fused end to end in sequence to form a resonant cavity link.

3. The high-power dual-comb spectrometer system according to claim 1, wherein: The first optical fiber amplifier (3) and the second optical fiber amplifier (4) comprise an optical isolator, a wavelength division multiplexer, and a gain optical fiber; the first optical fiber amplifier (3) and the second optical fiber amplifier (4) are single-stage or multi-stage cascade amplifier structures, and the gain optical fiber is a waveguide medium with a core doped with rare earth ions.

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